I'm running Windows XP Home Edition, 32-bit. I swear my desktop has a personal vendetta against me. This is a custom build, btw. I've owned it for over 10 years, and am moderately computer savvy. I seldom ever turn my computer off, and one day, for no apparent reason, it just turned itself off. I went through an entire list of things trying to solve this mystery. I still cannot figure it out. It won't even boot to any 'Safe mode' options, so even the 'Last known good' approach fails. I have unplugged every external device one at a time; then I disconnected and reconnected both hard drives one a time; I re-seated my memory cards; I looked at my BIOS -(and yes, the SATA setting was incorrect, so I changed it back); I replaced the old power supply; and I pulled the CPU, cleaned it and the heat-sink, and applied fresh thermal paste between the two. I still have the same problem. I can boot to the OEM installation CD, but the instant that it tries to boot from the hard drive, the computer immediately turns itself off. I have tried different hard drives - and I have tried everything from the Windows XP OEM installation 'Repair' option to actually re-partitioning a couple of hard drives and made several attempts to re-format and re-install Windows. I absolutely love Windows XP so I am now in the process of buying refurbished parts to build a new gaming system, one piece at a time, one month at a time. There came a point when I finally had to give up on my old system, may it R.I.Pieces. lol. Guess I'm stuck using my 'D3ll' laptop that runs Windows 10, which will never be as good as Windows XP, in my opinion. Anyway, if anyone can think of anything else that I could try, please offer your advice! Thank you!